Regular expression in java for validating numbers
Constructs beginning with a backslash are called escaped constructs.
We previewed escaped constructs in the String Literals section where we mentioned the use of backslash and Enter your regex: .
They create a new regular expression pattern object, every time you call.
Since most of the time we can just reuse the pattern, we don't need to spend time on creating and compiling pattern, which is expensive compared to testing a object to see if input string passes this regular expression pattern or not.
Another problem is that you allow logins of more than 20 characters. If you would like to use a regular expression, then let the regular expression do the hard work. The only thing the regular expression matcher can't handle is a null string. The hyphen is also literal if it comes at the end of the character class. Also, your regex requires at least two characters, though your rules require just one.
class provides a couple of methods with an inbuilt support of regular expression e.g.split method, replace All() and matches method, which can be used for this purpose, but they have a drawback.
That's all on this post about How to check if a String contains numbers or any numeric digit in Java.
Enter your regex: \s Enter input string to search: I found the text " " starting at index 0 and ending at index 1.
In this regex tutorial, we will learn to validate user entered phone numbers for a specific format (in this example numbers are formatted in north American format) and if numbers are correct then reformat them to a standard format for display. ([0-9])$"; Pattern pattern = Pattern.compile(regex); for(String email : phone Numbers) Output: 1234567890 : true 123-456-7890 : true 123.456.7890 : true 1 : true (123) 456 7890 : true 12345678 : false 12-12-111 : false List phone Numbers = new Array List(); phone Numbers.add("1234567890"); phone Numbers.add("123-456-7890"); phone Numbers.add("123.456.7890"); phone Numbers.add("1"); phone Numbers.add("(123) 456 7890"); //Invalid phone numbers phone Numbers.add("12345678"); phone Numbers.add("12-12-111"); String regex = "^\(?
I have tested formats including 1234567890, 123-456-7890, 123.456.7890, 1, (123) 456 7890, and all such combinations.
Enter your regex: \d Enter input string to search: a No match found.
Enter your regex: \D Enter input string to search: 1 No match found.